The red in the Nazi flag was meant to attract Communists.
Mussolini was a Communist and had edited their newspaper.
More than that, according to Erik von Kuehnelt-Leddihn in his book "Leftism Revisited", the original Nazi flags were MADE from Communist flags. They simply sewed a Swastika over the Hammer and Sickle on the flags they already had.
The Nazis were a splinter group off the communist movement in Germany. Oh, and they were also a Homosexual club when they started.